In metal working operations, coolant is commonly applied to the contact point or area of the tool and workpiece. The coolant prevents overheating by absorbing heat due to the working operation and also lubricates the contact area to reduce friction therefore reducing the amount of heat generated by frictional contact of the tool and workpiece. In stock removing processes, coolant further serves to flush metal chips away from the contact area.
In stock removing processes, a conventional tool utilized comprises a generally disc-shaped tool body with stock removing surfaces arranged thereon. The stock removing surfaces may be located about the periphery of the tool body as shown by U.S. Pat. Nos. 3,176,675 to Bomba or 3,777,443 to Shaw. Alternatively, the stock removing surfaces may project from one of the faces of the tool body as exemplified by WIPO Publication No. WO 92/06817 or U.S. Pat. No. 5,137,402 to Ball et al. This latter type of tool is generally referred to as a "face-mill" type tool.
Regardless of the arrangement of stock removing surfaces on the body of a tool, processes of removing stock material from workpieces usually necessitates coolant being delivered to the area of contact of the tool and workpiece for reasons such as those discussed above.
In tools having stock removing surfaces located about the periphery thereof, it is conventional to provide a reservoir means in the tool which is connected via unidirectional passages to the periphery of the tool. Upon rotation of the tool and introduction of coolant into the reservoir, centrifugal force causes the coolant in the reservoir to flow through the passages and exit at the periphery of the tool. Examples of this type of structure are shown in the aforementioned U.S. Pat. Nos. 3,176,675 and 3,777,443. In the production of gears and the like, gear type tools possessing this same type of reservoir and coolant passage structure are disclosed by U.S. Pat. No. 5,094,039 to Yoshioka and Japanese Patent Application No. 63-16921.
Another means for providing coolant to a rotating cutter having blades on the periphery thereof is disclosed by U.S. Pat. No. 4,414,783 to Vincent. In this arrangement, a coolant system is combined with a blade guard. Coolant channels are included in the blade guard and coolant is delivered over most of the cutter radius and on both sides of the cutter in order to contact the entire cutting area.
Of course, it can be seen that in tools having stock removing surfaces arranged on a face of the tool body, the reservoir and unidirectional passage arrangement applicable to those peripheral-type of tools discussed above will not provide coolant to the stock removing surfaces. Therefore, other approaches of providing coolant to a face of a tool body have been developed.
In tools having stock removing surfaces arranged on a face of the tool body it is known from U.S. Pat. No. 5,140,780 to Lincoln to substantially surround the entire tool with a housing. In the housing, coolant is directed against the tool to clean it while the rotation of the tool sprays the coolant against the workpiece.
In another arrangement, U.S. Pat. No. 4,528,779 to Wiener teaches grinding gears with the tool and workpiece immersed in a cooling lubricant bath to ensure coolant always being available at the grinding point. However, this procedure is very cumbersome and time consuming.
In grinding spiral bevel gears, passing a perforated grinding wheel through a feeder block comprising a sump containing grinding fluid is disclosed by U.S. Pat. No. 4,951,426 to Kurono et al. The rotating wheel passes through the feeder block and grinding fluid flows into the perforations in the grinding wheel. The grinding fluid is then carried to the workpiece. While this apparatus may be applicable to a grinding wheel, it does not lend itself to a plurality of cutting blades arranged about the face of a tool body.
In the tools where a plurality of stock removing surfaces, such as cutting blades, are arranged about the face of a tool body or head, it has been conventional to supply coolant to the contact area by spraying. An example of this is shown by the previously mentioned WO 92/06817 which discloses spraying coolant from the central attachment screw of a milling tool onto the stock removing surfaces of the tool. It is also well known to spray coolant onto a tool and workpiece via one or more externally arranged coolant hoses having their outlets located near the contact area.
In spraying, however, delivery of coolant originates from outside of the contact area and does not always adequately supply the tool and workpiece with sufficient coolant. There remains a need for supplying coolant directly to the point of contact of the tool and workpiece in tools having a plurality of stock removing surfaces arranged about the face of the tool body.